December 21, 2012 can't come soon enough for me, so that on Christmas Day we can all point at Geryl and laugh at him like Nelson Muntz from "The Simpsons."

You can easily see that you compass can point to a wrong direction when you move close to big metallic objects and power lines.

http://en.wikipedia.org/wiki/Magnetic_declination

Edit: Of course the poles in the first place aren't exactly simply things, we could have a north pole pop up anywhere, but by pop up we really mean 'over a few hundred years'.

I'm going to guess/hope the various pole shift pages are up to date, if not there is a thread over in Misc about it, right about here.

When an air-plane pilot is heading for the landing strip he uses his compass to confirm that he is heading in the right direction and thus approaching the right airstrip.
They divided the 360 degree into 36 angles each in 10 degree jumps.
So runway 18 would be 180 degree heading on your compass.

Because it is a 10 degree interval, the real heading could be between 175.5 and 185.4 on you compass all pointing to the rounded up 180 degree.
Now the magnetic pole is on the move so your magnetic compass would change slightly over the years. And in this case the runway is not aligned to 185.4 degree any-more but 185.6 or so the rounding off means that they assign it to the next 10 degree interval 190 = runway 19.

Of course the 2012 hoaxers take this and run with some big claim but it has zip effects on Earth. Only birds might fly off a bit off course because they use the magnetic fields.

Here you see how the poles have been moving since 1831

http://www.scientificamerican.com/article.cfm?id=are-the-earths-magnetic-p